keywords

Question 1

states of matter

Answer 1

the distinct form of a substance that tells whether it is a solid, a liquid, or a gas

Question 2

solid

Answer 2

a state of matter where the substance has a fixed shape and volume, and cannot be compressed

Question 3

liquid

Answer 3

a state of matter where the substance has a fixed volume, but can flow and change its shape

Question 4

gas

Answer 4

a state of matter where the substance has no fixed shape or volume, and can be compressed easily

Question 5

diffusion

Answer 5

the automatic mixing of liquids and gases as a result of the random motion of their particles

Question 6

atom

Answer 6

the smallest part of an element that can still be recognized as the element

Question 7

element

Answer 7

a substance made up of only one type of atom. An element cannot be broken down chemically into any simpler substance

Question 8

periodic table

Answer 8

an arrangement of elements in the order of their atomic numbers, forming groups and periods

Question 9

group

Answer 9

all the elements in the columns, labelled 1 to 7 and 0, down the periodic table

Question 10

compound

Answer 10

a substance made when two or more elements are chemically bonded together

Question 11

molecule

Answer 11

a group of atoms bonded together

Question 12

nucleus (of an atom)

Answer 12

the very small and dense central part of an atom, which contains protons and neutrons

Question 13

electron

Answer 13

a tiny particle with a negative charge that orbits the nucleus in atoms or ions

Question 14

proton

Answer 14

a tiny positive particle found inside the nucleus of an atom

Question 15

neutron

Answer 15

a dense particle found in the nucleus of an atom. It is electrically neutral, carrying no charge

Question 16

atomic number

Answer 16

the number of protons (which equals the number of electrons) in an atom. It is sometimes called the proton number

Question 17

mass number

Answer 17

the number of protons plus neutrons in the nucleus of an atom

Question 18

energy level (or shell)

Answer 18

an area in an atom, around its nucleus, where electrons are found

Question 19

electronic structure

Answer 19

a set of numbers to show the arrangement of electrons in their energy levels (or shells)

Question 20

isotope

Answer 20

atoms that have the same number of protons but different number of neutrons, i.e. they have the same atomic number but different mass numbers